Method for obtaining a rubber composition including a thermoplastic filler

Abstract

A process for the preparation of a rubber composition for the manufacture of tires is presented. The composition is based on one or more diene elastomers, one or more reinforcing fillers, and a crosslinking system. The composition includes particles of one or more thermoplastic materials chosen from amorphous thermoplastic materials and semicrystalline thermoplastic materials, with the glass transition temperature of the amorphous thermoplastic material or materials and the melting point of the semicrystalline thermoplastic material or materials varying from 80° C. to 300° C. The particles exhibit a volume-average diameter of less than or equal to 200 μm.

The invention claimed is: 
     
       1. A process for preparing a rubber composition usable in manufacturing tyres, the composition being based on one or more diene elastomers, one or more reinforcing fillers, and a crosslinking system, the composition further including particles of one or more thermoplastic materials chosen from amorphous thermoplastic materials and semicrystalline thermoplastic materials, with a glass transition temperature of the one or more amorphous thermoplastic materials and a melting point of the one or more semicrystalline thermoplastic materials being in a range of from 80° C. to 300° C., and with the particles exhibiting a volume-average diameter of less than or equal to 200 μm, the process comprising:
 incorporating in at least one diene elastomer, during a non-productive stage, at least one reinforcing filler to form a first mixture, and thermomechanically kneading the first mixture in one or more kneading events until a maximum temperature of between 130° C. and 200° C. is reached; 
 cooling the first mixture to a temperature of less than 60° C.; 
 subsequently incorporating in the first mixture, during a productive stage, a crosslinking system, particles of at least one amorphous thermoplastic material having a glass transition temperature of less than 200° C., and particles of at least one semicrystalline thermoplastic material having a melting point less than 200° C. to form a combined mixture; and 
 kneading the combined mixture up to a maximum temperature of less than 80° C., 
 wherein particles of at least one amorphous thermoplastic material having a glass transition temperature greater than or equal to 200° C. and particles of at least one semicrystalline thermoplastic material having a melting point greater than or equal to 200° C. are introduced during the non-productive stage or during the productive stage or during both the non-productive stage and the productive stage. 
 
     
     
       2. The process according to  claim 1 , wherein the at least one thermoplastic material is or are chosen from a group that includes: polypropylenes, polyethylenes, polystyrenes, acrylonitrile/butadiene/styrene copolymers, polymethyl methacrylates, polyamides, polyphenylene ethers, polycarbonates, polyacetals, thermoplastic polyurethanes, thermoplastic fluoropolymers, and polyesters. 
     
     
       3. The process according to  claim 2 , wherein the polyesters are chosen from a group that includes: polyethylene terephthalates, polybutylene terephthalates, and polyethylene naphthoates. 
     
     
       4. The process according to  claim 2 , wherein the fluoropolymers are chosen from a group that includes: copolymers of tetrafluoroethylene and hexafluoropropene, copolymers of tetrafluoroethylene and perfluorovinyl ether, copolymers of tetrafluoroethylene and ethylene, and polyvinylidene fluoride. 
     
     
       5. The process according to  claim 1 , wherein the glass transition temperature of the at least one amorphous thermoplastic material and the melting point of the at least one semicrystalline thermoplastic material are in a range of from 80° C. to 200° C. 
     
     
       6. The process according to  claim 1 , wherein the particles exhibit a volume-average diameter of between 50 and 100 μm. 
     
     
       7. The process according to  claim 1 , wherein the particles of the at least one thermoplastic material are present at a content of from 10 to 50 phr. 
     
     
       8. The process according to  claim 1 , wherein the particles of the at least one thermoplastic material are present at a content of from 20 to 40 phr. 
     
     
       9. The process according to  claim 1 , wherein the at least one diene elastomer is or are chosen from a group that includes: polybutadienes, natural rubber, synthetic polyisoprenes, butadiene copolymers, isoprene copolymers, and mixtures thereof. 
     
     
       10. The process according to  claim 9 , wherein the at least one diene elastomer is a butadiene/styrene copolymer. 
     
     
       11. The process according to  claim 1 , wherein the at least one reinforcing filler is or are chosen from a group that includes: silica, carbon black, and mixtures thereof. 
     
     
       12. The process according to  claim 1 , wherein the at least one reinforcing filler is or are present at a content of between 20 and 200 phr. 
     
     
       13. The process according to  claim 1 , wherein the at least one reinforcing filler is or are present at a content of between 30 and 150 phr.